5 TERILIZA TION AND DISINFECTION. 117 Kronig, as its boiling-point is i68°-i78° C., and thus sufficiently high to kill spores. The use of cumol for the sterilization of catgut has been carefully investigated by Clarke and Miller.1 Ligatures of silk and silkworm-gut are boiled in water immediately before using, or are steamed with the dressings, or placed in test-tubes plugged with cotton and steamed in the steam sterilizer. At present, in most hospitals, instruments are boiled before using in a 1-2 per cent, soda solution. Plain water has the disadvantage of rusting the instruments, and during the operation they are either kept in the boiled water or in carbolic solution. Andrews makes special mention of the fact that the instruments must be com- pletely immersed to prevent rusting. During the operation the wound is frequently washed with normal salt solution, applied by sterile marine or gauze sponges. The water and the salt solution used for surgical pur- poses are to be sterilized before using, either by steaming for a prolonged period, or by the intermittent method. Large hospitals are generally furnished with special appa- ratus for supplying sterile distilled water in large quantity. To La Place belongs the credit of observing that the efficacy of bichlorid of mercury is greatly increased by the addition of a small amount of acid, by which the penetration is increased and the formation of insoluble album mates lessened. The knowledge that the action of germicides is chem- ical, and that the destruction of the bacteria is due to the combination of the germicide with the mycoprotein, is apt to lessen our confidence in the permanence of their action. Geppert has shown of bichlorid of mercury that in the reaction between it and anthrax spores the vitality of the latter seems lost, but that the precipitation of the bichlorid from this combination by the action of ammo- nium sulphid restores the vitality of the spore. 1 Bull, of the Johns Hopkins Hospital, Feb. and March, 1896.